Electric knife switches with simplified contact pressure adjustments



Fig. 2

Fig.3

I G. SI'VIY,

ELECTRIC KNIFE SWITCHES WITH SIMPLIFIED CONTACT PRESSURE ADJUSTMENTS Original Filed May 18,

Dec. 5, 1967 INVENTOR George 'Siviy a ATTORNEY WITNESSESI v WW United States Patent Oliice 3,355,815 Patented Dec. 5, 19167 3,356,815 ELEGTREC KNIFE SWITCHES WITH SIMPLIFIED CONTACT PRESSURE ADJUSTMENTS George Siviy, Monroeville, Pa., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania @riginal application May 18, 1962, Ser. No. 195,838, now Patent No. 3,240,911, dated Mar. 15, 1966. Divided and this application Aug. 24, 1965, Ser. N 0. 482,070

4 Claims. (Cl. 200162) ABSTRACT OF THE DISCLOSURE This invention relates, generally, to electrical switches and, more particularly, to switches of the knife-blade type suitable for carrying relatively large amounts of current. More specifically, two generally parallel spaced blades of a switch are formed of a material having a high electrical conductivity and mechanical stiffness. Rotatable studs are threaded into the blades for drawing the blades together to obtain the desired contact pressure between the blades and the associated hinge and break contact members. Spherical contact buttons are mounted on the blades which engage one side of the hinge contact away from the break contact beyond the stud which pivotally supports the blades.

This is a division of application Ser. No. 195,838, filed May 18, 1962, now Patent No. 3,240,911.

In switches of the knife-blade type it is important that the contact portions of the blades make good contact with the stationary hinge and break contact members. Heretofore, it has been customary to utilize cup-washers drawn together with a bolt and nut to obtain the desired contact pressure. Since the design of the cup-washer permits rel-a tively little deflection as a spring member, loading and adjustments are critical. During the operation of knifeblade switches employing cup-washers, wear on the contact portions of the switches makes periodic readjustment of the cup-washers necessary to obtain proper contact pressure. Readjustment of contact pressure, necessary to compensate for wearing of parts is diflicult since a fraction of a turn of the nut increases the contact pressure considerably.

An object of this invention is to provide a switch of the knife-blade type which does not require the use of cup-Washers to obtain contact pressure between the contact members of the switch.

A more specific object of the invention is to provide for utilizing long lever arms as spring members to maintain contact pressure between the contact members of a switch.

Another object of the invention is to provide a switch having a relatively large range of adjustment of contact pressure.

A further object of the invention is to compensate for misalignment of the blades of a switch.

Still another object of the invention is to provide for readily adjusting the contact pressure of a knife-blade switch.

A more general object of the invention is to provide a knife-blade switch which is simple in operation and which may be economically manufactured and installed.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with one embodiment of the invention, two generally parallel spaced blades of a switch are composed of zirconium copper which has a high electrical conductivity and mechanical resistance to bending, or stiffness, thereby making it applicable for current carrying spring members. Rotatable studs are threaded into the blades between the hinge contact member and the break contact member for drawing the blades together, thereby utilizing the spring characteristics of the blades to obtain the desired contact pressure between the contact members of the switch. Compensation for misalignment of the blades is obtained by brazing silver buttons on the sides of the blades adjacent the hinge contact and the break contact. The buttons have spherical surfaces which engage the sides of the hinge contact member and the break contact member.

For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description taken in conjunction with the accom panying drawing, in which:

FIGURE 1 is a view, in plan, of a disconnect switch embodying the principal features of the invention;

FIG. 2 is a view, in side elevation, of the switch shown in FIG. 1;

FIG. 3 is a view, in plan, of a modified hinge structure for the switch; and

FIG. 4 is a view, in side elevation, of the hinge shown in FIG. 3.

Referring to the drawing, and particularly to FIGS. 1 and 2, the disconnect switch shown therein comprises a hinge contact member 11, a break contact member 12 spaced from the hinge member 11 and two spaced, generally parallel blades 13 pivotally mounted on the hinge member 11 and engaging the break mmber 12 when the switch is closed. The hinge member 11 has a base 14 and an upright portion 15. Likewise, the break member 12 has a base 16 and an upright portion 17. The bases 14 and 16 may be attached to a suitable supporting structure (not shown).

As shown more clearly in FIG. 1, the two blades 13 are disposed on opposite sides of the upright portions 15 and 17 of the hinge member 11 and the break member 12, respectively. The blades are pivotally attached to the upright portion 15 by a pin 18 which is retained in position by a cotter key 19. When the switch is closed, the blades 13 engage opposite sides of the upright portion 17 of the break contact member 12, thereby completing an electric circuit through the switch. It will be understood that power conductors may be connected to the base portions 14 and 16 of the hinge member 11 and the break member 12, respectively. p

In order to compensate for misalignment of the blades 13, a plurality of contact buttons or members 21 are secured to the inner surfaces of the blades. The members 21 may be composed of silver, or other suitable material, and they may be attached to the blades by brazing, or other satisfactory method. Each contact member 21 has a generally spherical surface for engaging one side of the upright portion 15 of the hinge contact membr 11 or the upright portion 17 of the break contact member 12, thereby maintaining good contact between the contact members 3 of the switch even though the parts ofthe switch may be slightly out of alignment.

With a view to maintaining the desired contact pressure between the contact members of the switch without utilizing cup-washers, the blades 13 are preferably composed of zirconium copper which is a copper base alloy having a high electrical conductivity and suflicient mechanical stiffness, or resistance to bending, to permit, the blades to be utilized as current carrying spring members. As shown in FIGS. 1 and 2, two adjusting studs22 are threaded into the blades 13 between the hinge member 11 and the break member 12. Each stud 22 has right and left hand threads 45 and 47 respectively, thereby drawing the two blades together as the studs are rotated and maintaining a predetermined lateral spacing between the blades 13 adjacent to each stud 22. In this manner the spring characteristic of the blades is utilized to obtain the desired contact pressure between the contact members of the switch. Lock nuts 23 are provided on the studs to retain them in proper adjustment. The studs may be easily readjusted to compensate for wear of the contact members, thereby maintaining the correct contact pressure between the contact members of the switch.

Also, the studs provide a rigid blade construction which with the stabilizing effect of the four contact members 21 equally spaced around the pivot pin 18 make a satisfactory hinge joint. Since the necessary contact pressure is obtained by the spring action of the blades, no cupwashers or other means of obtaining contact pressure are required.

The blades 13 may be operated in a manner well known in the art, as by means of an actuating lever 25 attached a to the blades. If desired, a latch (not shown) of a type also well known in the art may be provided for retaining the blades in the closed position. The latch may be operated by means of a hook stick (not shown).

An alternate hinge construction is shown in FIGS; 3 and 4 in which each blade 13' has two integral contact fingers 24 which extend beyond a shouldered stud 25 mounted in the upright portion 15' of the hinge member 11 having a base 14. Each finger24 has a contact button or member 21 having a spherical surface for engaging a side of the upright portion 15'. A nut 26 may be tightened on the threads 25A and 25B of the stud 25 to draw the blades 13' against shoulders 27 on the stud 25, thereby, deflecting the blades 13 to obtain the desired contact pressure between the contact members because of the spring characteristic of the zirconium copper blades. A washer 28 composed of anti-friction material, such as Teflon may be provided between each blade andthe upright member 15 to reduce friction. It will be understood that an adjustable stud, like one of the studs 22 shown in FIGS. 1 and 2, may be utilized to obtain the desired contact pressure between the blades 13' and the break contact member which is not shown in FIGS. 3 and 4.

The alternate construction shown in FIGS. 3 and 4 has the additional advantage that the operation of the hinge provided is independent of or unaffected by the spring characteristics of the contact blades. This arrangement avoids any relative lateral movement of the contact blade 13 outside the normal plane of operation during opening or closing of the switch shown in FIGS. 3 and 4.

From the foregoing description it is apparent that the switch structure incorporates relatively long lever arms for spring members. This results in greater deflection at a given load. Therefore, variations in deflection due to manufacturing tolerances and from operational wear are not critical. The electrical conductivity and mechanical stiffness or spring characteristic of the zirconium copper blades enables them to be utilized as current conducting spring members, thereby making it possible to eliminate cup-washers, which have undesirable characteristics, from the switch structure.

Since numerous changes may be made in the abovedescribed construction and different embodiments of the invention may be, made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In an electrical switch, in combination, a hinge contact member having an upright portion, a break contact member having an upright portion spaced from the hinge member, two spaced, generally parallel blades disposed on opposite sides of the upright portions of the hinge member and the break member, said blades being composed of a material having a high electrical conductivity and mechanical stiffness, a stud having shoulders disposed between the blades for pivotally attaching the blades to the uprightportion of the hinge member, each blade having contact fingers at one end extending beyond said stud with contact members secured to and disposed on the contact fingers, said contact members on the fingers having generally spherical surfaces engaging only one side of the upright portion of the hinge contact member away from the break contact member beyond the stud, and threaded means on the stud for drawing the blades against the shoulders on the stud to maintain contact pressure between the contact members on the fingers and the hinge contact member independently of the operation of the blades.

2. In an electrical switch, in combination, a hinge contact member having an upright portion, a break contact member having an upright portion spaced from the hinge member, two spaced generally parallel blades disposed on opposite sides of the upright portions of the hinge member and the break member, said blades being composed of a material having a high electrical conductivity and m nical stiffness, a stud having shoulders disposed between the blades for pivotally attaching the blades to the upright portion of the hinge member, each blade having contact fingers at one end extending beyond said stud with contact members secured to and disposed on the fingers, said contact members on the fingers having generally spherical surfaces engaging only one side of the upright portion of the hinge contact member away from the break contact member beyond the stud, and threaded means on the stud for drawing the blades against the shoulders on the stud to maintain contact pressure between the contact members on the fingers and the hinge contact member independently of the operation ofsaid blades and additional threaded means in theblades for drawing the other end of the blades toward the break contact member.

3. In an electricalswitch, in combination, a hinge contact member having an upright portion, a break contact member having an upright portion spaced from the hinge member,two spaced generally parallel blades disposed opposite sides of the upright portions of the hinge member and the break member, said blades being composed of zirconium copper having a high electrical conductivity and mechanical stiffness, a stud having shoulders disposed between the blades for pivotally attaching the blades to the upright portion of the hinge member, each blade having contact fingers at one end extending beyond said stud with contact members secured to and disposed on the fingers, said contact member on the fingers having generally spherical surfaces engaging only one side of the upright portion of the hinge contact member away from the break contact member beyond the stud, and threaded means on the stud for drawing the blades against the shoulders on the stud to maintain contact pressure between the contact members on the fingers and the hinge contact member independently of the position of said blades with respect to the break contact member, said contact fingers being relatively diverging with respect to each other in a direction away from said stud.

4. In an electrical switch, in combination, a hinge contact member having an upright portion, a break contact member having an upright portion spaced from the hinge member, two spaced generally parallel blades disposed on opposite sides of the upright portions of the hinge member and the break contact member, said blades being comsure between the contact members on the fingers and the hinge contact member independently of the operation of said blades and adjustable means threaded into the blades with right and left hand threads for drawing the other end posed of zirconium copper having a high electrical con- 5 of the blades toward the break contact member.

ductivity and mechanical stiffness, a stud having shoulders disposed between the blades for pivotally attaching the blades to the upright portion of the hinge member, each blade having contact fingers at one end extending beyond said stud with contact members secured to and disposed on the fingers, said contact members on the fingers having generally spherical surfaces engaging only one side of the upright portion of the hinge contact member away from the break contact member beyond the stud, threaded means on the stud for drawing the blades against the shoulders on the stud to maintain contact pres- References Cited UNITED STATES PATENTS 670,145 3/1901 Bossert 200l62 1,935,516 11/1933 Musgrave 200l62 X 2,546,366 3/1951 Lindae 200170 X ROBERT S. MACON, Primary Examiner.

15 ROBERT K. SCHAEFER, Examiner,

H. BURKS, Assistant Examiner. 

1. IN AN ELECTRICAL SWITCH, IN COMBINATION, A HINGE CONTACT MEMBER HAVING AN UPRIGHT PORTION, A BREAK CONTACT MEMBER HAVING AN UPRIGHT PORTION SPACED FROM THE HINGE MEMBER, TWO SPACED, GENERALLY PARALLEL BLADES DISPOSED ON OPPOSITE SIDES OF THE UPRIGHT PORTIONS OF THE HINGE MEMBER AND THE BREAK MEMBER, SAID BLADES BEING COMPOSED OF A MATERIAL HAVING A HIGH ELECTRICAL CONDUCTIVITY AND MECHANICAL STIFFNESS, A STUD HAVING SHOULDERS DISPOSED BETWEEN THE BLADES FOR PIVOTALLY ATTACHING THE BLADES TO THE UPRIGHT PORTION OF THE HINGE MEMBER, EACH BLADE HAVING CONTACT FINGERS AT ONE END EXTENDING BEYOND SAID STUD WITH CONTACT MEMBERS SECURED TO AND DISPOSED ON THE CONTACT FINGERS, SAID CONTACT MEMBERS ON THE FINGERS HAVING GENERALLY SPHERICAL SURFACES ENGAGING ONLY ONE SIDE OF THE UPRIGHT PORTION OF THE HINGE CONTACT MEMBER AWAY FROM THE BREAK CONTACT MEMBER BEYOND THE STUD, AND THREADED MEANS ON THE STUD FOR DRAWING THE BLADES AGAINST THE SHOULDERS ON THE STUD ON MAINTAIN CONTACT PRESSURE BETWEEN THE CONTACT MEMBERS ON THE FINGERS AND THE HINGE CONTACT MEMBER INDEPENDENTLY OF THE OPERATION OF THE BLADES. 